A computer network is a collection of interconnected computing devices that can exchange data and share resources. A physical connection between devices within the network is generally referred to as a link. In order to increase efficiencies, a single link may “channelized” to carry multiple data streams. Specifically, the available bandwidth of the link may be segmented into multiple channels. These channels may be further channelized into smaller channels, also referred to as sub-channels.
In a packet switching network, such as an Ethernet network, the computing devices communicate data by dividing the data into variable-length blocks called packets, which are individually routed across the network from a source device to a destination device. The destination device extracts the data from the packets and assembles the data into its original form. Computing devices that perform packet switching, such as high-speed routers or Ethernet switches, include switch fabrics that are configured specifically for the demands of packet switching, including high-speed packet switching. Multiplexing of multiple channels in packet switching networks allows for statistical multiplexing gain. Oversubscription of link bandwidth is permitted in packet switching networks. Packet queues may cause varying packet transfer delay, and such delay is tolerated and managed by the sending and receiving device as well as the intermediate routers and other devices of the packet switching network.
A circuit switching network is one that establishes a circuit between nodes before endpoints may communicate. Communication occurs across the circuit switching network as if the nodes were physically connected with a continuous, dedicated circuit from the source to the destination. Computing devices that perform circuit switching have switch fabrics that are configured specifically for circuit switching. In a circuit switching network, the delay variation for transmission of any data through the network across a given circuit is small (on the order of microseconds), as opposed to packet switching, which may experience packet transfer delay variation in the range of tens to hundreds of milliseconds. In this way, circuit switching networks guarantee bandwidth for any given circuit. However, circuit switching networks do not allow for oversubscription or forms of dynamic bandwidth allocation or dynamic re-channelization of a link such as statistical multiplexing gain. Examples of circuit switching devices include Synchronous Digital Hierarchy (SDH) signal cross-connect architectures that multiplex circuits at Synchronous Transport Signal-1 (STS-1) and higher, and Digital Cross-connect Systems (DACSs) that multiplex circuits below STS-1.
Due to their differences, some network environments implement both circuit switching devices and packet switching devices to handle different types of data communications. For example, a network service provider may deploy a set of devices to form a circuit-switched network for handling voice or other time-critical communications and a different set of devices to form a packet-switched network for data communications or other transmissions that may be less time-critical. This dual-network approach is costly to deploy and requires significant overhead to manage.